Tell MySQL to use the new readline interface even when an external
readline is being used.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Index: mysql_client-5.1.47/configure.in
===================================================================
--- mysql_client-5.1.47.orig/configure.in	2010-07-15 23:49:35.000000000 +0200
+++ mysql_client-5.1.47/configure.in	2010-07-15 23:50:03.000000000 +0200
@@ -2700,6 +2700,7 @@
 	    # this way we avoid linking commercial source with GPL readline
 	    readline_link="-lreadline"
 	    want_to_use_readline="yes"
+	    AC_DEFINE_UNQUOTED(USE_NEW_READLINE_INTERFACE, 1)
 	elif [test "$mysql_cv_libedit_interface" = "yes"]
 	then
 	    # Use libedit